Starting and operating circuit for high pressure arc lamps



March 14, 1961 s, D ETAL 2,975,331

STARTING AND OPERATING CIRCUIT FOR HIGH PRESSURE ARC LAMPS Filed Dec. 16, 1959 FIG.I

22 22 M 21 1 I 4 I J 5 25 4 6 3 24 26 5 INVENTORS MANUEL S. DIAZ TAYLOR D. WHITENACK JR KM? ALA/hr ATTORNEYS STARTHVG AND OPERATING CIRCUIT FOR HIGH PRESSURE ARC LANIPS Manuel Sariego Diaz, Union, and Taylor D. Whitenack, Jr., Livingston, N.J., assignors to Engelhard Hanovra, Inc., a corporation of New Jersey Filed Dec. 16, 1959, Ser. No. 859,938

6 Claims. (Cl. 315-163) The present invention deals with a starting and operating circuit for high pressure are lamps and more particularly with a radio frequency lamp starting circuit in combination with a lamp operating circuit.

The line voltage usually required for starting high pressure arc lamps, especially high pressure are lamps of the compact type, is from approximately 2 to times that at which the lamp normally operates depending upon gas pressure, electrode spacing, electrode geometry and other particular lamp characteristics. High pressure are lamps usually require a series ballast to reduce the voltage at the lamp terminals. Radio frequency power is advantageously employed in the lamp starting circuit to ionize the high pressure gas filling of the lamp to minimize the high voltage starting potential which would otherwise be required at the source.

The invention comprises a novel lamp starting and operating circuit which permits the employment of a greatly reduced line voltage for high pressure are lamps, especially zenon lamps. The invention is especially concerned with a radio frequency starting circuit in combination with means whereby the lamp is capable of substantially instantaneous ignition and which mean-s conditions the radio frequency field for optimum starting results.

According to the invention it has been found that the employment of a low pressure gas-filled light transmissive envelope positioned near the high pressure are lamp influences the path of the radio frequency field for more eflicient ignition of the high pressure are lamp. In addition to influencing the radio frequency field, the low pressure gas filled envelope is immediately ionized and emits light which when directed on the high pressure are lamp also contributes to the optimum ignition of the high pressure arc lamp.

It is an object of the invention to provide a high pressure arc lamp starting and operating circuit whereby the high pressure are lamp is capable of instantaneous ignition. It is another object of the invention to provide a lamp operating circuit in combination with a radio frequency lamp ignition circuit and with a low pressure gas filled envelope positioned in the radio frequency field at a location near the high pressure arc lamp, whereby the low pressure gas envelope aids in the ignition of the high pressure arc lamp. Other objects and advantages of the invention will become apparent from the description hereinafter following and the drawings forming a part hereof, in which:

Figure l is a diagrammatic illustration of the operat ing and ignition circuit of the invention, and

Figure 2 illustrates a partly cross-sectional and partly diagrammatic view of a modification of the invention.

The invention deals with an ignition and operating system for high pressure are lamps, especially compact type arc lamps whereby a low pressure gas filled envelope positioned in the radio frequency field at a position near the high pressure are lamp, e.g. less than about one inch ited States Patent" 6 from the lamp, provides substantially instantaneous ignition of the high pressure are lamp.

While the ignition and operating system as hereinafter more particularly described may be advantageously applied for the ignition and operation of high pressure vapor are lamps, it is especially applicable for the ignition and operation of a compact type are lamp containing solid electrodes spaced apart to provide a discharge path from a few millimeters to less than two centimeters in length in an enclosed atmosphere consisting of zenon at a pressure exceeding about one atmosphere.

In accordance with the invention, the operating circuit comprises a pair of leads 1 and 2 connected or connectable to a source of direct current 3 and to electrodes 4 and 5 of a high pressure discharge lamp 6 with a resistance ballast 7, e.g. a variable resistance, and a coil 8 connected in series in a circuit lead, e.g. in lead 1, in series with the lamp 6.

The ignition circuit comprises a radio frequency circuit connected in parallel with the operating circuit and with ignition leads 9 and 10 connected across the DC. source 3, the leads 9 and 10 being connected to a converter 11 through switch 12 for converting the DC. to AC. Leads 13 and 14 lead from the converter 11 and are connected across the primary winding 15 of ignition transformer 16. Leads 17 and 18 are connected across the secondary winding 19 of the transformer 16 and across the primary winding 20 of radio frequency transformer 21. A spark gap 22 is connected between the leads 17 and 18 with a radio frequency capacitor 23 connected in the lead 18. The series coil 8 is the secondary winding of the radio frequency transformer 21. A radio frequency by-pass capacitor 24 is connected across the leads 1 and 2 between the coil 8 and the ballast 7 to restrict the radio frequency components across the lamp 6. A low pressure gas filled envelope 25 with or without a reflector 26 and containing a rare gas, e.g. argon, is supported or mounted by any conventional mounting means (not shown) in the radio frequency field at a location near the high pressure are lamp 6.

When the switch 12 is closed causing the ignition circuit to apply a high radio frequency voltage through the transformers 16 and 21 to the lamp electrodes 4 and 5 a somewhat scattered radio frequency field is created around the lamp 6 and rad-lo frequency components are applied to the electrodes 4 and 5. Ordinarily the radio frequency voltage after some seconds ionizes the high pressure gas filling of the lamp 6 and the lamp ignites. However, in accordance with this invention it has been found that when a gas filled low pressure light transmissive envelope is positioned near the high pressure arc lamp 6, the low pressure rare gas filled envelope 25 presents a low impedance path in the radio frequency field around the lamp 6 and the low pressure gas is ionized instantaneously. It is believed that the low impedance path presented by the low pressure gas envelope concentrates and channels the radio frequency field between the envelope 25 and the lamp 6 and in addition the ionized low pressure gas filling of the envelope 25 emits light directed onto the lamp 6. The combination of the concentration of the radio frequency field and the emitted light accelerates the ignition of the high pressure are lamp 6 by lowering the impedance of the high pressure gas to radio frequency. After the lamp 6 is ignited, the switch 12 is opened and the lamp continues to operate under the voltage of the source 3 through the ballast 7. Figure 2 illustrates a modification of the invention in that a high pressure are lamp 27 is mounted in a reflector 28 and supported therein by supports 29 and 30 mounted on the reflect-or 28. The ignition and operating voltage passes through leads 1 and 2 to the conductive supports 29 and 30 and the lamp 27. A light transmissive low pressure gas filled envelope is mounted on the reflector by means or support 32am is positioned erase tome map 27 and spaced rearwardly therefrom. While the invention has been described specifically with regard to Figuresi and 2, var-ions modifications contemplated witiii'n the seeps of the appended claims.

What is claimed is: p r 1, An operating and ignition system for a high pressure gaseous discharge-lamp containing an io-iiizabl'e atmosphere and spaced electrodes, comprising said lamp, electrical leads connected to the electrodes, a coil in one of the leads in series with the lamp, thecoil being a component of a radio frequency ignition means, a capacitor connected across the lamp, the coil, lamp, capacitor and said leads comprising a radio frequency circuit, and a low pressure gas-filled envelope positioned near the lamp at a lo'catimi within the radio frequency field of the radio frequency circuit. p 2'. An operating and ignition system according to claim 1, comprising'a ballast means in one of the leads in series with said coil, the capacitor being connected across the leads between the ballast and coil. I H p 3. An operating and ignition system "according to claim 1, wherein the lamp contains xenon at a pressure above about one atmosphere.

4. An operating and ignition system according to claim 1, comprising a source of D.C., the leads connecting the lamp to the source of DC. A

5. An operating and ignition system according to claim 1, comprising a reflector, the low pressure envelope being mounted in said reflector, the reflector being directed toward the lamp.

6. An operating and ignition system for a high pressure gaseous discharge lamp containing an ionizable atmosphere and spaced electrodes, comprising said lamp, electrical leads connected to the electrodes, a low pressure gasfilled envelope positioned near the high pressure gaseous discharge lamp, radio frequency means for applying radio frequency signals to said high pressure lamp and said gas-filled envelope, and circuit means for operating said discharge lamp.

References Cited in the file of this patent UNITED STATES PATENTS 2,856,563 Rively on. 14, on 2,870,379 Bird Jan; 20, 1959 2,916,669 Retzer et a1. Dec. 8, 1959 OTHER REFERENCES Eccker Abstract No. 151,616, Dec. 18, 1951. 

